Container



July 1, 1969 c, ELLIOT 3,452,896

CONTAINER Filed April 29. 1968 r Sheet 0r2 FIG] INVENTOR. NEIL C. ELLIOTATTORNEY N. c. ELLIOT July 1, 1969 CONTAINER Sheet 2 of 2 Filed April29, 1968 F/GIE F/GJZ Fla 1]? INVENTOR. 4 NEIL C. ELLIOT ATTORNEY- UnitedStates Patent U.S. 'Cl. 220-60 9 Claims ABSTRACT OF THE DISCLOSURE Aplastic container lid which is stackable without wedging, is easilyejected from its forming mold, and is peripherally scalable to acontainer body. Sealing, which is in the corners for noncircular shapes,is accomplished by snapping relatively deep peripherally spaced socketsin the lid over a projection extending outwardly from the mouth of thecontainer body.

This application relates to a container, and more particularly to aplastic lid for closing the opening of a complementary container body.

Thermoplastic containers are becoming increasingly useful in packagingand storage application of all types. These containers are usuallyclosed with snap-on lids of the insert or of the over cap variety, whichare made of relatively thin plastic to minimize material costs and tofacilitate rapid production rates. The lids must seal tightly yet beeasily removable by a consumer. However, it has been found that in highspeed mass production operations, close tolerances cannot beconsistently maintained on the mating peripheral sealing portions of thelid and container body which are adequate to provide a tight sealbetween the mating parts. Thus when the sealing portion of the body, forexample, is oversize (or the lid is undersize) the lid will either notfit the body at all, or if it is forced onto the body by automatedcapping equipment in the filling line, will be too tight to beconveniently re moved by the consumer. On the other hand, if the sealingportion of the body is undersize (or the lid oversize) the lid fit istoo loose and it may fall off during handling, or mayinadequatelyprotect the packaged product. Frequently it is not possiblefor the consumer to know whether the lid is properly engaged on thebody, or only partially engaged thereon.

In addition, lids and bodies of this nature must also be stackablewithout wedging together, since in high speed production operations theymust be consistently individually fed successively from stackedformations. Ease of release of the container lid and body from theirrespective forming molds is also a design consideration, sinceprojections extending opposite to the general outward flare of the sidesof the parts inhibit axial ejection from the molds. With suchconfigurations the molded part must be flexed laterally to permit theformed projection to proceed beyond the corresponding forming portion ofthe die. Sufficient lateral flexing to permit axial ejection from themold without damaging the parts is especially difficult with relativelystiff thermoplastics. Design modifications to alleviate the initiallymentioned production tolerance problem, therefore, cannot be madewithout considering the effect on the provisions made for stacking andreleasing the lid and mating body parts from their forming molds.

'It has been found that this dilemma of difficulties has beeneffectively solved by the present invention. There is provided astackable, snap-on, tight sealing, readily removable, plastic lid havingperipherally spaced means for sealing to a complementary stackablecontainer body. Both lid and body may be produced at high rates whileconsistently providing a seal between the parts.

Accordingly, it is an object of the present invention to provide animproved container lid which avoids the prior art difficulties discussedabove.

It is an additional object of this invention'to provide a snap-oncontainer lid which audibly permits knowledge of when the lid is inplace on the container body.

It is another object of this invention to provide a container lid andbody combination which permits relaxation of molding tolerances for themating sealing portions of the parts, while still providing an effectivecontainer seal.

It is another object of this invention to provide an improved tightsealing, stackable container lid adapted for use in automated packagingoperations, which can be manufactured at high production rates with aminimum of difficulty incurred in its ejection from the forming mold.

A further object of this invention is to provide a noncircular, snap-oncontainer lid which accomplishes the above-described objects.

An additional object of this invention is to provide a snap-on containerlid of relatively stiff thermoplastic material which fulfills theabove-described objects.

These and other objects will in part be obvious and will in part appearhereinafter.

These and other objects are accomplished by providing a plasticcontainer lid comprising a top wall and a skirt extending downwardlyfrom the periphery of the top wall, the skirt having a plurality ofperipherally spaced sockets which extend outwardly with respect to theperiphery of the top wall, the sockets being adapted to confine amarginal portion situated adjacent the open end of a complementarycontainer body, each socket having an upper wall portion, and a lowerwall portion which extends substantially inwardly beyond the outer limitof the body margin, the skirt having a stacking abutment at its lowerend beneath each socket which is adapted to support the lid in spacedrelationship upon the upper wall portion of the socket of a similarlyconfigured lid. The lids are preferably of noncircular configurationwith the stacking abutments and sealing sockets located in each of thecorners thereof. Strengthening furrows may be provided in the skirtabove the sealing sockets to minimize lateral flexing of the lid inthese areas.

In describing the overall invention, reference will be made to preferredembodiments illustrated in the accompanying drawings in which:

FIG. I is a top plan view of a lid embodying the invention;

FIG. 11 is a perpective view of the lid of FIG. I in closure sealingengagement on a container body;

FIG. III is an enlarged, partial, sectional view taken along the line'IIIIII of FIG. II;

FIG. IV is a partial, sectional, elevational perspective view of anested stack of the lids of FIG. I; and

FIG. V is a sectional elevational view taken along the line VV of FIG.IV.

With reference to the drawings, wherein identical numerals refer toidentical parts, there is shown in FIGS. I and II a generallyrectangular, thin wall, plastic stackable noncircular lid indicated as10, for a container body generally indicated (FIG. II) as 12. As shown,container body 12 is of thin wall plastic, and is noncircular inhorizontal cross section having a radially outwardly extending marginalprojection 13 adjacent to and extending around an opening in the topportion thereof. Lid 10 comprises elongated, generally fiat top wall 14,having converging edges 16 defining corners 18 at the points ofconvergence of edges 16. Lid 10 further comprises a skirt 20 (FIG. III)extending downwardly from the periphery of top wall 14, having in eachof its four corners 18, a radially outwardly opening verticallyextending strengthening furrow 22 adjacent the periphery of top wall 14.A radially inwardly extending, generally U-shaped locking protrusion 24is provided in skirt 20 spaced from and axially aligned below furrows 22in each of corners 1-8 of lid 10. The innermost surface 26 of protrusion24 is situated radially outwardly with respect to the innermost portion28 of the outer surface of the furrow 22, as can be seen from FIGS. IIIand V. Between furrows 22 and protrusions 24 in each corner 18 of lid11}, there is provided an intermediate, member 30 of L-shaped radialcross section having an upper leg 32, connected at the inner end thereofwith the wall which defines furrow 22. Member 30, as shown, extendsoutwardly by means of upper leg 32 and downwardly along vertical leg 34,which in turn merges with the uppermost wall of locking protrusion 24.Intermediate member 30, and protrusion 24 in each of the four corners 18of lid define socket 36 between protrusion 24 and furrows 22 forsealingly confining margin 13 of body 12 when the lid is in place on thebody all as shown in the left side of FIG. III. Socket 36 extendsoutwardly with respect to the periphery of lid top wall 14.

The configuration of the remainder of peripherally extending skirt otherthan in the corners of lid 10 is depicted on the right of FIG. III. Anintermediate member 38 is also provided having a shape similar to thatin corners 18, in that horizontal portion 40 is connected at one endthereof to vertical wall 42 which. has a smooth outer surface, asopposed to the furrowed configuration of the corner skirt portion.Upright leg 44 of intermediate member 38 is jointed at its lower end toshallow C-shaped projection 46 which projects inwardly with respect toupright leg 44 to a lesser extent than does rounded protrusion 24 withrespect to vertical leg 34 of intermediate member 30 in lid corners 18.Consequently cavity 48 along the sides of lid 10 is not nearly asconfining by virtue of its lower configuration as are sockets 36 in thecorners thereof. Lift tab 48 extending radially out from the end oflower leg 50 of U-shaped protrusion 24 may be provided to facilitateremoval of the lid by the fingers of a consumer. This projection may beeither continuous around the full periphery of the lid or situated onlyat spaced intervals there around.

To place lid 10 on body 12, the lid is initially rested atop peripheralprojection 13 of the body in an aligned manner. Pressure is then exerteddownwardly so that the rounded inner surface of protrusion 24 in eachcorner 18 of lid 10 is resiliently deflected outwardly or resilient bodyprojection 13 deflected inwardly depending on which of the two is madeof the stiffer material. The outer end 52 of projection 13 camminglyfollows the rounded inner surface of substantially inwardly extendingprojection 24 as a result of downwardly exerted pressure, until it hasmoved beyond the longitudinally extending portion of projection 24, whenit thereupon encounters no further resistance and expands against theupper wall of socket 36 with an audible snap. The body margin 13 is thenconfined within this socket on the upper side by the horizontal portion32 of intermediate member 30, and on the lower side by the uppermostportion of U-shaped projection '24. This action occurs in each of thefour corners of rectangular lid 10. When the lid is in place on thecontainer body, a clearance 54 may exist between the inner surface ofthe lid skirt 30 and the outer end of the body peripheral margin orprojection 13 as a result of relaxed tolerances on each of these parts,yet the lid is still held tightly in place in each of the deep cornersockets. As depicted in FIG. III, some locking may also occur around theremainder of the periphery to a lesser extent than in the corners, as aresult of the position of shallow C-shaped projection 46 situatedbeneath and laterally inwardly of the outer end of projection 13.

To remove lid 10 from body 12, the bottom face of corner lift tab 48 ofwhich there may be a plurality when the configuration is noncircular,i.e., one located in each corner, is gently pushed upwardly by the thumbor finger of a user in either of the four corners of the container,

while another finger laterally spaced inwardly presses down on the topsurface of lid top wall 12. This results in a prying away of lid 10 fromprojection 13 of body 12 in the particular corner area chosen to beopen, in a manner which is generally the reverse of the way in which thebody projection was audibly snapped into the lid socket. After the lidhas been pried away from the edge in the corner area it may then beeasily grasped between the fingers and progressively peripherally peeledaway from the remainder of the upper portion of body 12.

Stackability of lids 10 without resulting in a wedging action occurs asshown in FIGS. IV and V. Outer surface 56 of outwardly extending portion32 of intermediate member 30 of the skirt 20 of a lower lid, in each ofthe four corners thereof, acts as a supporting surface for outerabutment surface portion 58 of the U-shaped protrusion of an upper lidso as to support the upper lid in stacked, spaced relationship withrespect to the lower lid. The substantial inward extent of corner locks24, with respect to the maximum lateral extent of the intermediatemember provides considerable load bearing corner contact betweensurfaces 56 and 58 of adjacently stacked lids as shown in FIG. V. Thisresults in a stable stack not susceptible to having the contacting partsof either of the lids forced beyond the other so as to provideundesirable wedging. Some stacking support may occur along the sides ofthe lids other than in the corners as depicted in FIG. IV, as a resultof the contact between the lower side 60 of shallow C-shaped projection46 of an upper lid and the outer surface of the horizontal portion ofthe intermediate member of a lower lid. Stackability (wedge resistance)is, however, primarily dependent on corner rather than side contact.

FIG. V also depicts the relationship between the projection 24 of anupper lid and furrow 22 of a lower lid with the latter functioning as astacking aid when two lids are stacked together. Furrow 22 of the lowerlid is in lateral alignment with projection 24 of the upper lid, so thatprojection 24 may if necessary at least partially fit within furrow 22in the skirt of the lower lid. This provides corner clearance to permitthe upper lid to stackingly fit over the lower lid should the dimensionsof the two lids be such as to prevent this from otherwise occurringbecause of dimensional variations resulting from the relaxed tolerancesbetween the adjoining parts. In other words, though projection 24 of theupper lid is not shown in FIG. V as fitting within furrow 22 of a lowerlid, the space is available to achieve this should it be required forother adjacently stacked lids of slightly different dimensions. Furrow22 because of its contour also provides strength in each corner toresist lateral lid deflection. This deflection, which is prone to occurbecause of the thin wall construction is problematical in that if it isexcessive, wedging of the lids will occur. Furrow 22 also decreases thetotal amount of undercut which must be overcome in strippingthermoformed lids from their forming molds. Specifically, if the furrowwere not present, the portion of the lid skirt where the furrow is nowlocated would have to be forced laterally inwardly a sufficient amountto move it beyond the laterally inwardly extending mold projectiondefining deep U-shaped lid protrusion 24. This extra lateral movementwhich is more difficult to accomplish at the end of the skirt joined tothe top wall than at the free lower end, would increase the formingcycle and therefore the manufacturing cost, since the lid would have tobe left longer in the forming mold so as to cool and set it suflicientlyto permit deflecting it laterally without permanently distorting it,which could occur if the plastic were in a softer, more pliable state.Furrows 22 appear only in the corners where stacking contact primarilyoccurs. The tendency toward lateral flexing of the sides other than inthe corners during handling need not be of concern with the presentdesign, and configurations to overcome it are unnecessary.

The above description and particularly the drawings are set forth forpurposes of illustration only and are not to be taken in a limitedsense.

The relatively deep, reversely angled, spaced corner locks of the lid ofthe present invention must extend laterally inwardly to a greater extentthan that of the inwardly extending projections the remainder of the lidskirt since this is the area of the lid which is responsible for holdingit onto the container body. The inward extent of these cornerprojections as well as the extent to which they are provided around theperiphery must not be excessive, since difficulties could then beencountered in ejecting the lid from its forming mold. In general themaximum inward extent of the peripherally spaced lid skirt lockingprojections should extend to between about .015 to .030 inch inwardlybeyond the maximum lateral dimension of the upper marginal projection ofthe container body. The inner surfaces of these relatively deep lockingprojections should be rounded to facilitate cammingly guiding theprojections past the peripheral margin of the body or vice versa.

Since dependence for locking the lid onto the container body is based onperipherally spaced, reversely angled projections in the lid skirt, theperipheral configuration of the skirt between these projections mayvary. In place of the shallow C-shaped configuration shown in thedrawings, for example, a straight vertical portion could be used, ornothing at all, i.e., a discontinuity could be provided in this area ofthe lid. A peripherally continuous, shallow reversely angled projectionis preferred, however, since this configuration can, to a degree,function in cooperation with the spaced locking projections to provide astacking abutment and to assist in sealing the lid on the containerbody. Furthermore, it provides the same general outer appearance in thesides as that which is necessary in the corners, so as not to detractfrom the pleasing overall continuous aesthetic appearance of the lid.

The strengthening furrows peripherally located in the lid skirt at thepoints where locking and stacking primarily occur function to strengthenthese areas against the tendency to flex laterally which may causetelescoping when a plurality of lids are stacked together, and whichcould result in a premature release of the lid from the container body.In addition these furrows provide insurance that the deep lockingprojections of one lid will clear the skirt of an adjoining lid whenbeing stacked thereon without requiring tight molding tolerances toachieve this consistently. These furrows function also to minimize theextent of undercut which must be overcome during the mold ejection stepof the fabricating process over that which would be encountered if theywere not present. The furrows should extend inwardly from the remainderof the lid-periphery for between about .005 to .020 inch.

Positioning of the locking projections around the lid periphery may beaccording to any pattern desired. However, a particular problem occurswith noncircular shapes, Where due to the configuration the lid sidesradially flex outwardly around the periphery, but at the same time areput under tension and even tend to flex slightly inwardly in the cornerareas when pressure is exerted from above. Thisinherent characteristicof noncircular shapes is used to advantage in a preferred embodiment ofthe present invention, in that the locking projections, surfaces ofwhich have a stacking function, are positioned in the area of theperiphery where outward flexing is nonexistent or at a minimum, i.e., inthe corner areas.

Though use of interrupted lid locking and stacking projections areuniquely applicable to noncircular type lids in the present invention,it should be understood that these may be used with circular lids, withease of mold discharge being the primary consideration in such cases.Possible configurations include square, oval, oblong, triangular and thelike.

The material from which the lid is formed may be any plastic capable ofbeing molded from sheet material in accordance with the previouslymentioned design parameters. Thermoplastics generally have theadvantages of being tough, difficult to break under ordinarycircumstances, and have sufficient strength to be fabricated relativelythinly from web stock for economy purposes, since the containerscontemplated herein are of the throw away type which are generally meantto be nonreusable after consumption of the initial contents. Theresulting lid, when formed in this manner is unitary in construction,has no seams, and is of the thin wall variety having a generally uniformthickness between about 2 to mils.

Usable thermoplastics are polymers based on styrene, polyolefins such asfor example, polyethylene, or polypropylene, and polyvinyl chloride.

Particularly useful materials for forming these lids are relativelystiff thermoplastics having a flexural modulus in excess of about100,000 p.s.i., and preferably between 250,000500,000 p.s.i., such as,for example, rubbermodified polystyrene or polystyrene which preferablyhas a rubber compound grafted or mechanically blended therein, e.g.,acrylonitrile, butadiene, styrene copolymers. In addition, it has beenfound necessary to have at least one and preferably both of the matingportions of the container constructed of these materials in order toobtain the audible security snap feature which is heard when the lid isforced onto the container body. This feature of the invention clearlyand decisively permits the user to know when the lid is sealed on thebody. These materials are tough and resilient even when thin and kept atlow temperatures, and are usually inert to most foods which may bepackaged in the container. Unfortunately, however, these thermoplasticsare relatively stiff and have very little tendency to shrink away fromundercut portions of the forming mold on cooling, in comparison to theshrinkage obtained with softer materials. It has, therefore, beenparticularly difficult to mold reversely angled portions of thesematerials having a sufficient lateral extent tol resist wedging, yetwhich may be ejected from the mold without difliculty. The interruptedconfiguration of the present invention provides equivalent capabilitiesin this area for lids of thermoplastic materials having a flexuralmodulus in excess of about 100,000 p.s.i., with those of softermaterials.

In general, the present lid finds particular utility in automated andsemiautomated packaging lines for foods and other consumer items, andwherever storage space dictates that a plurality of lids must be stackedin telescoping relation. The assembled container comprising the lid andcontainer body is tightly sealed, yet easily openable and resealable.The lids have improved structural stability, and may be easily dispensedwith little or no difficulty from the bottom of a stack, while at thesame time presenting fewer manufacturing difficulties in the moldingoperation, particularly with respect to with drawal of the lid from themold. Consequently, high manufacturing rates may be maintained at verylow costs. Dimensional tolerances'of the mating parts may be relaxedwithout a corresponding increase in reject rate or decrease in thesealing quality of the lid. These tolerances may range between abouti040 inch whereas the tolerances for similarly positioned conventionallymanufactured parts is about 1.020 inch.

It will be understood that many variations and modifications of theembodiments herein described will be obvious to those skilled in theart, and may be carried out without departing from the spirit and scopeof the invention.

What is claimed is:

1. A plastic container lid comprising a top wall and a skirt extendingdownwardly from the periphery of the top wall, said skirt having aplurality of peripherally spaced sockets which extend radially outwardlywith respect to the periphery of the top wall, said sockets beingadapted to confine a radially outwardly extending marginal portion of acomplementary container body, such portion being situated adjacent anopen end of said body,

each socket having an upper wall portion and a lower wall portion, saidlower wall portion being adapted to extend substantially inwardly beyondthe outer limit of the body marginal portion, said skirt having astacking abutment at its lower end beneath each of said sockets adaptedto support said lid in stacked relationship upon the upper wall portionof the socket of a similarly configured lid.

2. The structure of claim 1 wherein the lid has a noncircularconfiguration, with the sockets located in the corners thereof.

3. A noncircular plastic container lid comprising:

(a) a top wall having converging edges defining corners;

(b) a skirt extending downwardly from the periphery of the top wallhaving in each corner:

(I) a radially outwardly opening vertically extending strengtheningfurrow adjacent the periphery of the top wall;

(II) an inwardly extending rounded protrusion below said reverselytapered furrow, the innermost surface of said protrusion beingsubstantially radially inwardly of the maximum radial dimension of aperipheral marginal portion situated adjacent the opening of acomplementary container body, said innermost surface of said protrusionbeing radially outward of the radially innermost portion of the outersurface of said vertically extending furrow;

(III) an intermediate member of L-shaped radial cross section connectingat the free edge of its long leg with the lower end of the wall of saidfurrow and extending outwardly and downwardly, the end of the downwardlyextending portion connecting with the uppermost edge of said protrusion,said intermediate member defining a socket between the protrusion andthe furrow into which may audibly snap said margin of the containerbody, the outer surface of said outwardly extending long leg portion ofthe intermediate member acting as a support on which rests theprotrusion of an upper lid while said resting protrusion at leastpartially fits within the groove provided by the furrow in the skirt ofa lower lid when two of such lids are stacked together, in order tomaintain the top walls of said stacked lids spaced from each other.

4. The structure of claim 3 wherein the lid has a generally rectangularconfiguration.

5. A plastic container comprising:

(a) a thin wall, open top, plastic body of noncircular horizontal crosssection having a projection extending radially outwardly around theopening in the top portion thereof;

(b) a thin wall plastic lid for the body having:

(A) a top wall having converging edges defining corners;

(B) a skirt extending downwardly from the periphery of the top wallhaving in each corner:

(I) a radially outwardly opening vertically extending strengtheningfurrow adjacent the periphery of the top wall;

(II) an inwardly extending U-shaped locking protrusion spaced from andaxially aligned below said furrow, the innermost surface of saidU-shaped protrusion being radially outward of the innermost portion ofthe outer surface of the furrow;

(III) an intermediate member connecting at one edge with the skirt atthe lower end of said furrow and extending outwardly and downwardly, theend of said downwardly extending portion connecting with the uppermostleg of said U-shaped protrusion, said intermediate member defining asocket between the furrow and the U-shaped protrusion into which theprojection at the top of the container body may be audibly snapped tosealingly confine said projection therein, the outer surface of saidoutwardly extending portion of the intermediate member acting as asupport against which rests the lower leg of the U-shaped protrusion ofan upper lid while said protrusion at least partially fits within thegroove provided by the furrow in the skirt of a lower lid when two ofsuch lids are stacked together, in order to maintain the top walls ofsaid stacked lids spaced from each other.

6. The container of claim 5 wherein the peripheral portions of the skirtintermediate the U-shaped locking protrusions in the corners extendinwardly to a lesser extent than that of the locking protrusions.

7. The container of claim 5 wherein the plastic is a relatively stiffmaterial having a fiexural modulus within the range of between about250,000500,000 p.s.i.

8. The container of claim 7 wherein the plastic is an acrylonitrile,butadiene, styrene copolymer.

9. The container of claim 7 wherein the tolerances on' the lateraldimensions of the lid skirt and, the container body projection rangebetween about 1.040 inch.

References Cited UNITED STATES PATENTS 3,077,284 2/ 1963 McLaughlin 220-3,122,264 2/ 1964 Davis 220-60 X 3,178,051 4/1965 Edwards 220-603,237,803 3/ 1966 Edwards 220-6O X 3,351,227 11/1967 Collie 22060FOREIGN PATENTS 1,141,584 12/ 1962 Germany.

JOSEPH R. LECLAIR, Primary Examiner.

J. R. GARRETT, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,42%,896 Dated July 1, i269 Neil C. Elliot It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 7, line 21, Claim 3, delete the words "reversely tapered.

mUmLD NU SEALED FEB 171970 Amen:

Edward u Fletcher, 3:. -m. m.

oommissioner of Patents Attesting Officer

